SPML_ST_IDENTIFIER is an SAP Structure so does not store data like a database table does but can be used to process "SPML Identifier for Identities" Information within sap ABAP programs. This is done by declaring abap internal tables, work areas or database tables based on this Structure. These can then be used to store and process the required data appropriately.
i.e. DATA: wa_SPML_ST_IDENTIFIER TYPE SPML_ST_IDENTIFIER .
Below is the documentation avaialable and full details of the fields which make up this Structure.
|Data Type||length (Decimals)||Check table||Description||Conversion Routine|
|User Name in User Master Record|
|BP_PERSON_GUID||SIM_BP_PERSON_GUID||RAW||16||GUID of a Business Partner Identification Number|